Wiring a house on the inside of VB,with no penetrations?...

[Don P]

I guess its been a couple of years ago now. My partner had never seen a flying squirrel and we were removing a 30 year old onduline roof and putting down metal. It was log, cathedral and heavy timber and they had flying squirrels.

The roof was 12/12 but not much scaffold needed on the strip, just stomp into the onduline corrugations and clean above and alongside. I fully expected major roof repairs from what we were seeing. They had been trying to find someone for 3 years and had gotten full value out of the old roof but thankfully it had held.

For the uninitiated... we really don't want to go digging the yuk and joy out of your house  :D. This one turned out to be quick and easy for everyone.

Anyway, we were taking a break sitting on the roof deck, DB was above me closer to the ridge. Motion caught my eye. A flying squirrel popped out of the now open ridge, takes a short bound to DB's shoulder from the back, and launches. On that end we are 40-50' up and actually, we are above the river there, that guy could have gone forever, but lit in a tree a hundred feet or so away. Don never knew what hit him till he saw it gliding.

[Sod saw]

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The National Electrical  Code is the guiding "bible" that is used in most places in the USA.  Most insurance companies as well as building inspectors require any electrical installation to comply with that code to be sure that the electrical work is safe, and safety is the number one goal when it come to electricity.  Many insurance companies will not pay for a loss if the electrical installation was never "inspected" and the loss is caused by said faulty electrical installation.  The result is often that the person who did the installation will pay for the loss.  To my knowledge, there has been no loss payments being refused  by an insurance company with a valid final electrical inspection by a qualified electrical inspector here in America.  

Good call Don, , , ,   As for boxes and number of conductors in those boxes. . . . The code book is made up of sections; sort of like chapters.  Those sections are numbered by subject.  Your box fill section is 370.  Within this section the code requires that two conductors be subtracted from the allowed fill for each switch or outlet.   Those conductors that are subtracted must be two of the largest conductors.  I suspect that most of your boxes will have only one wire gauge size so the math will be easy.  

Onward to the box fill. . . .  Using the example of 18 cubic inch steel box, the code allows 8 #12 gauge conductors.  With romex wire you will have 3 conductors per each run of 12/2 romex (2 carrying current and one ground).  Therefore 2 romex cables can enter (or leave) a box and still have room for the subtraction of those two conductors for the outlet (or switch).  Needless to say, 14 gauge wires will allow more conductors in a given size box.   10 gauge fewer.  3 wire romex is a bit more challenging as I find it hard to count all the way up to 4.

Using GFI breakers instead of outlets might save you from future repairs as the outdoor humidity sometimes attacks the GFI outlet circuitry.  Yes, even with in-use covers.  Will they want extra switched outdoor outlets for Christmas lights to plug into?

With all that cold and insulation do you all use triple pain glass windows?  My daughter will be building a new home soon with R-60  double walls etc. with the vapor barrier in the middle between outside and inside somewhat as you described.  The indoor side of the walls will be 2x4 studs so the mechanical systems will be "normal" but with no penetrations as your project requires.

We live near the shore of Lake Ontario but are in the woods.  Our friendly flying squirrels had taken up residence in our ceiling (roof). My daughters cat has been known to proudly present them to her at nite when she is in bed.   After removing the bird feeders we hung a large piece of metal window screen over the hole in the outside wall.  The screen had a weight on it so the hole was blocked by the screen preventing the critters from getting in. The ones within the house could push the screen aside to get out but we're unable to return as the screen fell back over the hole.  The operative word is LARGE piece of screen.

Sometimes a .22 rimfire will help but its hard to see them (the squirrels not the cat) at nite.

However, you are correct.  They are fun to watch gliding from tree to tree (or your house).


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[jake pogg]

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The National Electrical  Code is the guiding "bible" that is used in most places in the USA.  Most insurance companies as well as building inspectors require any electrical installation to comply with that code to be sure that the electrical work is safe, and safety is the number one goal when it come to electricity.  Many insurance companies will not pay for a loss if the electrical installation was never "inspected" and the loss is caused by said faulty electrical installation.  The result is often that the person who did the installation will pay for the loss.  To my knowledge, there has been no loss payments being refused  by an insurance company with a valid final electrical inspection by a qualified electrical inspector here in America.  

Good call Don, , , ,   As for boxes and number of conductors in those boxes. . . . The code book is made up of sections; sort of like chapters.  Those sections are numbered by subject.  Your box fill section is 370.  Within this section the code requires that two conductors be subtracted from the allowed fill for each switch or outlet.   Those conductors that are subtracted must be two of the largest conductors.  I suspect that most of your boxes will have only one wire gauge size so the math will be easy.  

Onward to the box fill. . . .  Using the example of 18 cubic inch steel box, the code allows 8 #12 gauge conductors.  With romex wire you will have 3 conductors per each run of 12/2 romex (2 carrying current and one ground).  Therefore 2 romex cables can enter (or leave) a box and still have room for the subtraction of those two conductors for the outlet (or switch).  Needless to say, 14 gauge wires will allow more conductors in a given size box.   10 gauge fewer.  3 wire romex is a bit more challenging as I find it hard to count all the way up to 4.

Using GFI breakers instead of outlets might save you from future repairs as the outdoor humidity sometimes attacks the GFI outlet circuitry.  Yes, even with in-use covers.  Will they want extra switched outdoor outlets for Christmas lights to plug into?

With all that cold and insulation do you all use triple pain glass windows?  My daughter will be building a new home soon with R-60  double walls etc. with the vapor barrier in the middle between outside and inside somewhat as you described.  The indoor side of the walls will be 2x4 studs so the mechanical systems will be "normal" but with no penetrations as your project requires.

We live near the shore of Lake Ontario but are in the woods.  Our friendly flying squirrels had taken up residence in our ceiling (roof). My daughters cat has been known to proudly present them to her at nite when she is in bed.   After removing the bird feeders we hung a large piece of metal window screen over the hole in the outside wall.  The screen had a weight on it so the hole was blocked by the screen preventing the critters from getting in. The ones within the house could push the screen aside to get out but we're unable to return as the screen fell back over the hole.  The operative word is LARGE piece of screen.

Sometimes a .22 rimfire will help but its hard to see them (the squirrels not the cat) at nite.

However, you are correct.  They are fun to watch gliding from tree to tree (or your house).


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Thank you yet again,that explanation of conductors and their math Really helps,as well as all other advice.
Super cool way of dealing with the squirrel problem,an inverse of a fish-trap funnel,that's very clever!:)
And yes,most often the windows around here are inert gas filled triple-pane. In spite of that they're inevitably quite a breach in the thermal envelope,you can feel how cold their surface is on cold days...
On a serious project such as your daughter's house sounds to be sometimes people install those neat insulated "shutter" drapes,the kind that slide in a channel on each side,to conserve heat in the night.
At times i thought of experimenting with the real rigid shutters just like they had in the past but with some type of foam lining to bear against the glass.
The truoble designing something like that would be the hardware to open and close these,as the old-style,simple forged kind went through the wall,and being a moving part would be difficult to seal.
Never did come up with solution to that,maybe nowadays there's some tricky electronic/cordless device that could be used!:)

[Joe Hillmann]

Is this on a home they live in and keep heated all the time or a cabin that cools off?

I ask because if it is heated all the time I would have no concern with having the vapor barrier behind some insulation.  But if it is allowed to cool to near freezing then warmed up , then  cool and warmed up again and again(such as at a weekend cabin) at the beginning and end of each cool-warm-cool cycle conditions will be perfect for large amounts of condensation to form between the vapor barrier and the insulation.  If that happens once or twice a year, it isn't a problem, if it is happening every day and what ever is behind the vapor barrier stays cold it could be a major problem.

[jake pogg]

Yes,thank you,got that though it took me some mental grunting to understand what you mean.

You're absolutely right;if allowed to freeze from the Inside it could form ice between the plastic VB and the (vapor) impermeable foam.And keep forming each cycle.

The place i'm working on now is a permanent residence,constantly heated. But Very good point,thanks.

  

[Joe Hillmann]

I discovered first hand how bad it can be.  We built a greenhouse this fall and as of now it is unheated, every day it goes from below freezing, up to the high 60's+, then back below freezing.  Every time the tempature of surfaces warms or cools to the dew point huge amounts of condensation  forms on the windows, ceiling and insulated walls.  If that condensation were to happen against the vapor barrier it would be a problem.